<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
<style>
  .active{
      color: red;
  }
</style>
<body>

<script src="../js/vue.js"></script>
<div id="app">
<!--  <h2 :class="active">{{message}}</h2>-->
<!--  <h2 v-bind:class="{key1: value2,key2:value2}">{{message}}</h2>-->
<!--  <h2 v-bind:class="{类名1: true,类名2:true}">{{message}}</h2>-->
<!--  <h2 class="title" v-bind:class="{active: isActive,line:isLine}">{{message}}</h2>-->
  <h2 class="title" :class="getClasses()">{{message}}</h2>
  <button v-on:click="btnClick">按钮</button>
</div>

<script>
  const app = new Vue({
    el: '#app',
    data: {
      message: "第一次，系统的学VUE",
      active: "active",
      isActive:true,
      isLine:true
    },
    methods:{
      btnClick:function (){
        this.isActive = !this.isActive;
      },
      getClasses:function (){
        return {active:this.isActive,line:this.isLine};
      }
    }
  })
</script>

</body>
</html>